FIG. 3 is a vertical cross section showing a pre-coupling state in which a torque converter (i.e., a work) is not coupled with a conventional testing device for the torque converter. FIG. 4 is a vertical cross section showing a post-coupling state in which the torque converter is coupled with the conventional testing device.
In FIG. 3 and FIG. 4, reference numeral 1 denotes a torque converter, and reference numeral 2 denotes a turbine portion which is disposed within the torque converter 1 and formed with a splined portion 2a on an inner circumferential periphery thereof. Reference numeral 3 denotes a stator portion of the torque converter 1 which is disposed in an upper part of the turbine portion 2 within the torque converter 1 and formed with a splined portion 3a on an inner circumferential periphery thereof.
The turbine portion 2 is rotatably supported by a bearing within the torque converter 1. The stator portion 3 is fixed to an inside of the torque converter 1. The torque converter 1 is placed onto a faceplate in such a state that a fitting sleeve portion 1a is located on an upper side.
On the other hand, a turbine shaft 4 and a stator shaft 5 are concentrically arranged in the testing device such that the turbine shaft 4 is disposed inside of the stator shaft 5. The turbine shaft 4 is rotatably supported, while the stator shaft 5 is fixedly disposed.
The turbine shaft 4 has a splined portion 4a on a lower end portion thereof which is to be engaged with a splined portion 2a of the turbine portion 2 of the torque converter 1. The stator shaft 5 has a splined portion 5a on a lower end portion thereof which is to be engaged with a splined portion 3a of the stator portion 3 of the torque converter 1. The turbine shaft 4 has an oil passage 4b formed at a central part of the turbine shaft 4. In FIG. 4, reference numeral 6 denotes a first support portion which rotatably and integrally supports the turbine shaft 4, and reference numeral 7 denotes a second support portion which fixedly supports the stator shaft 5.
In the above construction, upon carrying out a performance test of the torque converter 1, the turbine shaft 4 and the stator shaft 5 on the side of the testing device are driven to downwardly move from the pre-coupling position of the testing device relative to the torque converter 1 as shown in FIG. 3 by operating a cylinder, and inserted through the fitting sleeve portion 1a into the torque converter 1. Then, as shown in FIG. 4, the splined portions 4a and 5a of the turbine shaft 4 and the stator shaft 5 are brought into engagement with the splined portions 2a and 3a of the turbine portion 2 and the stator portion 3 on the side of the torque converter 1, respectively.
Subsequently, a torque converter oil (or automatic transmission fluid) is fed into the torque converter 1 through the oil passage 4b in the turbine shaft 4 of the testing device at an oil pressure of 2-4 kg/cm2. The torque converter oil enters from a lower end of the oil passage 4b into the torque converter 1 and passes through a clearance between an inner circumferential surface of the fitting sleeve portion 1a of the torque converter 1 and an outer circumferential surface of the stator shaft 5 and a through hole 5b which is formed in the stator shaft 5. The torque converter oil then passes through a clearance between the support portions 6 and 7 and is discharged to an outside through a drain hole 7a which is formed in the second support portion 7. Incidentally, in certain circumstances, while measuring a feed pressure of the torque converter oil which is fed through the oil passage 4b and a discharge pressure of the torque converter oil which is discharged from the drain hole 7a, the torque converter oil may be fed from the drain hole 7a into the torque converter 1.
Upon connecting (or engaging) the respective splined portions 4a and 5a of the turbine shaft 4 and the stator shaft 5 with the respective splined portions 2a and 3a of the turbine portion 2 and the stator portion 3 of the torque converter 1, there might occur an abutment (or an interference) between end faces of crests of teeth at the respective splined portions 4a and 5a of the turbine shaft 4 and the stator shaft 5 and end faces of crests of teeth at the respective splined portions 2a and 3a of the turbine portion 2 and the stator portion 3. In such a case, it is not possible to establish the connection (or engagement) between the respective splined portions 2a and 3a of the turbine portion 2 and the stator portion 3 and the respective splined portions 4a and 5a of the turbine shaft 4 and the stator shaft 5. The proportion of a probability of completing the connection by a first connecting operation to a probability of failing to establish the connection or engagement by the first connecting operation are substantially fifty-fifty.
In a case where the connection between the splined portions 2a and 3a and the splined portions 4a and 5a is not established by the first connecting operation, the testing device is temporarily moved upward and then moved downward to attempt a second connecting operation in order to establish the connection therebetween. In this case, the torque converter 1 is rotated to change phases of teeth of the respective splined portions 2a and 3a, thereby increasing a possibility to engage the crests of teeth of the splined portions of one of the testing device and the torque converter 1 with valleys of teeth of the splined portions of the other thereof. The prior art documents relating to the above conventional art are as follows.    Patent Literature 1: Japanese Patent Unexamined Publication No. 63-201548    Patent Literature 2: Japanese Utility Model No. 2599603